1. Field of the Invention
This invention is directed to controlling the torque reactions in joint devices, particularly automotive ball joint devices, and to methods and apparatus for achieving that result.
2. Description of the Prior Art
The closest prior art is represented by U.S. Pat. Nos. of Herbenar 3,395,441 of Aug. 6, 1968 and its divisional 3,430,327 of Mar. 4, 1969, as well as Herbenar 3,395,442 of Aug. 6, 1968 and its divisional 3,464,723 of Sept. 2, 1969. This prior art teaches applying a static preload on the internal components of ball joint devices and thereafter rotating a flanging tool on the stationary housing to close the open end while holding the static preload. It is said that the static preload takes into account the tolerance buildup in the components. Also for a static preload the torque of the stud relative to the housing will vary due to contact between the components. The problem with this approach is that the spin closure of the housing introduces a force that can increase or decrease the static preload significantly due to the unreliable reaction of the spin rollers in the tool which are spring loaded so they can yield to radially deform the housing during the closing step. A more reliable way to manufacture ball joints with consistent torque loading has not been known prior to the method and apparatus set forth herein.
The prior art also includes Scheublein et al U.S. Pat. No. 3,656,221 of Apr. 18, 1972 wherein there is disclosed a method for assembling ball joint components so as to eliminate internal clearance between components due to manufacturing tolerances. More specifically the load transmitting ball stud component of the ball joint assembly is supported in a fixed position independent of the housing and the housing support during the closing of the housing flange.
In providing automotive vehicles with ball joint devices in the suspension systems in some cases, it is important to the uniformity of the steering reaction to obtain a uniform feel. It is recognized that steering systems that are either too tight or too loose are highly undesirable as it has a direct effect on the handling characteristics of the vehicle.
In the past the production of ball joint devices has been affected by the range of tolerances in the several parts that make up the ball joint. Apparatus for assembling ball joints has been generally independent of the tolerance factors with the result that a mismatch of tolerances may produce high or low torque values between the ball stud and the housing.